1. Field of the Invention
The invention relates to wireless communication, and more particularly, to dynamic call setup according to real-time network conditions.
2. Description of the Related Art
In wireless telecommunication systems, Push-to-talk (PTT) capabilities are becoming popular with individual groups of users as well as service sectors. PTT can support a “dispatch” voice service that operates over standard commercial wireless infrastructures, such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), and global system for mobile communications (GSM).
FIG. 1 illustrates a prior art architecture 100 supporting PTT communications. The architecture includes the deployment of a single PTT server 112 region in conjunction with a carrier's CDMA infrastructure and packet data network. Other network servers, such as additional PTT servers, can be resident on the regional network 110. Each region of the PTT server 112 is deployed over a specific portion of a packet data network. The PTT server 112 within the region may be routing traffic between one or more Packet Data Service Nodes (PDSNs) in the carrier network. A communication device 102 that supports the PTT feature is in communication with a base station (BS) 104. Each BS 104 may be in communication with one or more base station transceiver (BTS) 114. The BSC 104 is in communication with a high speed network 106 and PTT communications received from the communication device 102 is sent through the base station 104 and the network 106 to a packet data service node (PDSN). The BS 104 provides a package control function (PCF) 105 to the communication between the PDSN and the communication device 102. The PDSN communicates with the high speed network 106 and a PTT server 112's network 108, which is connected to a PTT network 110. The PDSN forwards the PTT communications to a PTT server 112 in the PTT network 110. A radio access network (RAN) 116 includes the BSC 104 and the BTS 114.
The PTT server 112 handles PTT communications among members of a PTT group. The PTT server 112 receives a PTT communication from one member and forwards it to all members of the PTT group. The PTT communication is usually received as data packets from the network 110, and the PTT communication sent out by the PTT server 112 is also in data packet format. A packet data service node (PDSN) and a connected base station (BS) then establish through a BTS 114 a dedicated traffic channel to transmit the PTT communication to a receiving mobile client (a PTT member). In use, a user is granted the “floor” to talk to the members of his PTT group after the PTT server 112 grants his “floor” request and necessary network resources to support his PTT communication.
PTT communications are commonly used in public safety and disaster recovery scenarios in which a large number of public safety officers and rescue workers communicate among themselves through PTT communications. One of problems related to call setup for the PTT communications between a large number of users is the latency in during the call setup process. The latency may be due to resource allocation that is heavily dependent on network conditions.
Because PTT communications are commonly used in public safety and disaster recovery scenarios, as well as by other individuals and groups that desire to effect communication with minimal delays, low latency network performance during call setup is particularly important for PTT calls.
During periods of nominal operation, when system resources in wireless (or wired) network are generally available, PTT call setup procedures in a system that provides PTT call services (or other services) over a network that provides differing grades of services (Quality of Service—QoS) for distinct traffics are typically optimized to minimize latency performance. The optimization is generally based on the assumptions that requests for a certain grade or quality of service for that call will nominally succeed.
However, when the service is operated during network conditions such that requests for certain grade or quality of service for that call will typically not succeed, i.e. during period of high call volume and high resource utilization, the nominal call flow may exhibit behavior that exacerbates the resource utilization constraint. It is therefore desirous to have a system and method that gracefully adapt resource reservation requests during PTT call setups that are appropriate for current network conditions, and it is to such system and method this invention is primarily directed.